Since 1929, polychlorinated biphenyls (PCB) have been produced industrially. The outstanding properties of PCBS include thermal stability, resistance to oxidation, acid, bases and other chemical agents and excellent di-electric properties. Because of these properties, PCB fluids were used extensively for electrical transformers and capacitors.
The toxicity of PCBs has been known for several decades. PCBs cause yellow atrophy of the liver, fatty degeneration of the liver and dermatitis. In addition PCB is a suspected carcinogen. In 1966, the presence of PCB in environmental samples was discovered. Concern in the late 1960s and early 1970s about potential environmental hazards, coupled with its long-term stability, resulted in the 1976 ban on PCB manufacture and use (15 U.S.C.A. .sctn.2605(e)(2)(A)).
The largest remaining source of PCBs is liquid cooled electric transformers. Under current Environmental Protection Agency (EPA) regulations, there are two alternatives for possessors of PCB containing transformers, retrofill or replacement. Retrofill of existing equipment is usually the least costly and easiest for oil and Askarel.RTM. filled transformers.
There are numerous methods available for retrofilling PCB containing transformers, for example, U.S. Pat. Nos. 4,685,972, 4,124,834 4,425,949 and 4,483,717. These methods deal with removing the PBC liquid, flushing the transformer and refilling with a non-PBC liquid. All of these methods are specifically aimed at decontaminating useful equipment. More particularly, the novelty of those methods is frequently a more efficient or thorough process or a process that allows the transfomer to remain in service during the decontamination. The present invention does not pertain to this category of transformers.
Retrofilling may not be suitable for all PCB containing transformers. Transformers in poor condition, or which have failed, or which are no longer useful require replacement and disposal of the removed carcasses.
Disposal of replaced transformers has long presented the owner with a dilemma. Current EPA regulations allow for disposal of PCB transformers in Toxic Substances Control Act approved landfills, but only after draining and an 18 hour rinse. Although landfill is authorized, this disposal method is not eithout substantial potential for long term liability. The transformer carcass can still contain up to 2% of its nameplate volume (20 to 100 lbs) soaked within its internals and the original owner remains responsible, jointly and severally, under the Comprehensive Environmental Response Compensation and Liability Act (CERCLA or "Superfund").
The present invention is directed at decontaminating the components of PCB containing transformers. Once the transformers are decontaminated, the components can be disposed of as non-toxic, non-hazardous waste.